1. Field of the Invention
This invention relates to a method for preparing ethane and ethylene by reacting methane or a methane-containing natural gas in the presence of oxygen or an oxygen-containing gas.
2. Description of the Prior Art
Methane is one of the resources which are abundant in the world as a main component of natural gases. However, since methane has low reactivity, the greater part of methane is exhausted as a fuel, and the utilized methods as a raw material for chemical industries are available on a limited basis. In 1982, however, Keller and Virgin reported that ethane and ethylene are produced by partially oxidizing methane using various metal oxides as a catalyst in the presence of oxygen (Journal of Catalysis published in U.S.A. Vol. 73, pp. 9-19, 1982).
Since then, many reports have been made on the useful catalysts for this reaction, which is called as an oxidation coupling reaction for methane. In case of classifying these catalysts, alkali metals and alkaline-earth metals, and for example, rare-earth metals such as lanthanide or their combinations are used as these catalysts in the majority of these catalysts. In particular, there are many reports on the catalysts which mainly consist of alkaline-earth metal. For instance, it is disclosed in Japanese Pat. Laid-open No. 62-267243 that ethane and ethylene are produced using a catalyst of an alkaline-earth metal compound such as calcium oxide.
In most of the above cases, however, the conversion ratio of methane and the selectivity of C.sub.2 hydrocarbon in the product are still low and the abilities are not so high as a practical catalyst. Therefore, it is desired to develop the catalysts having more activity and high selectively.